The results of the new USGS study are published in the Journal Environmental Science and Technology (link to the study here).
Major findings of the study are:
- Nitrate transport to the Gulf of Mexico was 10% higher in 2008 than 1980.
- Nitrate concentrations increased considerably at two sites with low concentrations in 1980.
- Nitrate concentrations remained the same or increased at the other six sites, including those where concentrations were relatively high in 1980.
- Increases in nitrate concentrations in groundwater are contributing to increases in river concentrations.